Creating EclipseLink DBWS Services

Creating an EclipseLink DBWS Service from a Database Table

You can create an EclipseLink DBWSBuilder XML file with a <table> query operation, as follows:

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <properties>
    <property name="projectName">table_test</property>
    ... database properties ...
  </properties>
  <table
    schemaPattern="%"
    tableNamePattern="dbws_crud"
  />
</dbws-builder>

For more information, see "Creating EclipseLink DBWS Service from a Database Table".

Creating an EclipseLink DBWS Service from a SQL Statement

You can create an EclipseLink DBWS builder XML file with a <sql> query operation, as follows:

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  <properties>
    <property name="projectName">sql_test</property>
    ... database properties ...
  </properties>
  <sql name="employeeInfo" simpleXMLFormatTag="employee-info" xmlTag="aggregate-counts">
    <text>
      <![CDATA[select count(*) as "COUNT", max(SAL) as "MAX-Salary" from EMP]]>
    </text>
  </sql>
</dbws-builder>

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  <properties>
    <property name="projectName">sql_binding_test</property>
    ... database properties ...
  </properties>
  <sql name="findEmpByName" isCollection="true" isSimpleXMLFormat="true">  
    <text>
      <![CDATA[select * from EMP where EMPNO = ? and LAST_NAME = ?]]>
    </text>
    <binding name="EMPNO" type="xsd:int"/>
    <binding name="LAST_NAME" type="xsd:string"/>
  </sql>
</dbws-builder>

Creating an EclipseLink DBWS Service from a Stored Procedure

You can create an EclipseLink DBWS builder XML File with a <procedure> query operation, as shown in Example 1-7.

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  <properties>
    <property name="projectName">procedure_test</property>
    ... database properties ...
    </properties>
  <procedure
    returnType="empType"
    catalogPattern="SOME_PKG"
    schemaPattern="SCOTT"
    procedurePattern="GetEmployeeByEMPNO_DEPTNO"/>
  </procedure>
</dbws-builder>

For more information, see "Creating from a Stored Procedure".

Performing Simple Customization

By default, DBWSBuilder-generated eclipselink-dbws-schema.xsd file derives <element-tag> names from the database table metadata, as shown in Example 1-8.

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  >
  <xsd:complexType name="empType">
    <xsd:sequence>
      <xsd:element name="empno" type="xsd:int" xsi:nil="false"/>
      <xsd:element name="ename" type="xsd:string" xsi:nil="true"/>
      <xsd:element name="job" type="xsd:string" xsi:nil="true"/>
      <xsd:element name="mgr" type="xsd:int" minOccurs="0" xsi:nil="true"/>
      <xsd:element name="hiredate" type="xsd:dateTime" xsi:nil="true"/>
      <xsd:element name="sal" type="xsd:decimal" xsi:nil="true"/>
      <xsd:element name="comm" type="xsd:int" minOccurs="0" xsi:nil="true"/>
      <xsd:element name="deptno" type="xsd:int" xsi:nil="true"/>
    </xsd:sequence>
  </xsd:complexType>
</xsd:schema>

Use the NamingConventionTransformer to change an <element> tag to an attribute, as shown in Example 1-9.

public interface NamingConventionTransformer {
 
    public enum ElementStyle {
        ELEMENT, ATTRIBUTE, NONE
    };
 
    public String generateSchemaName(String tableName);
 
    public String generateElementAlias(String originalElementName);
 
    public ElementStyle styleForElement(String originalElementName);
}

For more information, see "Naming Convention for schema elements" in the EclipseLink documentation: http://wiki.eclipse.org/EclipseLink/Examples/DBWS/DBWSIntermediateAttribute.

Performing Intermediate Customization

The primary reason to use an EclipseLink SessionCustomizer is to enable programmatic access to the EclipseLink API. Using this API, you can retrieve the object-relational or object-XML mapping descriptors from the session, and then use these descriptors to add, change, or delete mappings. You could also consider turning off the session cache, or changing the transaction isolation level of the database connection.

The following example shows how to implement a org.eclipse.persistence.config.SessionCustomizer:

package some.java.package;
 
import org.eclipse.persistence.config.SessionCustomizer;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.sessions.DatabaseLogin;
 
public class MySessionCustomizer implements SessionCustomizer {
 
  public MySessionCustomizer() {
  }
 
  public void customize(Sesssion session) {
    DatabaseLogin login = (DatabaseLogin)session.getDatasourceLogin();
    login.setTransactionIsolation(DatabaseLogin.TRANSACTION_READ_UNCOMMITTED);
  }
}
 

In the DBWSBuilder builder XML file, specify if the customization applies to the ORM project or the OXM project, as the following example shows:

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  <properties>
    <property name="projectName">customize_test</property>
     ...
    <property name="orSessionCustomizerClassName">some.java.package.MyORSessionCustomizer</property>

or

<?xml version="1.0" encoding="UTF-8"?>
<dbws-builder xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  <properties>
    <property name="projectName">customize_test</property>
     ...
    <property name="oxSessionCustomizerClassName">some.java.package.MyOXSessionCustomizer</property>

For more information, see "Session Customization" in the EclipseLink documentation: http://wiki.eclipse.org/Introduction_to_EclipseLink_Sessions_%28ELUG%29#Session_Customization.

Performing Advanced Customization

You can customize an EclipseLink DBWS service by creating your own project.xml and sessions.xml files. Using your preferred utility, you can do the following:

• map your objects to your relational database in an EclipseLink relational project;

• map your objects to your XML schema in an EclipseLink XML project:

• create an EclipseLink sessions.xml file that references both projects.

In this way, you can control all aspects of the relational and XML mapping. This approach is best when you want to customize most or all details. See "Using Existing EclipseLink ORM and OXM Mappings" for more information.